On November 24, 1971, a man using the name Dan Cooper boarded Northwest Orient Airlines Flight 305 from Portland to Seattle. He was wearing a dark suit, a narrow tie, and sunglasses. Shortly after takeoff, he handed a note to a flight attendant informing her that he had a bomb in his briefcase. He demanded $200,000 in cash (approximately $1.5 million in today's dollars) and four parachutes. His demeanor was calm, polite, and specific. After the plane landed in Seattle and his demands were met, he released the 36 passengers and two of the three flight attendants. He then directed the crew to fly toward Mexico City at minimum airspeed, with the landing gear deployed and flaps at fifteen degrees. Somewhere over the forested wilderness of southwestern Washington State, he lowered the rear airstair of the Boeing 727, stepped into the darkness, and vanished.
No confirmed trace of D.B. Cooper—a name coined by a media transcription error—has ever been found. The FBI investigated the case for 45 years before formally suspending active investigation in 2016. It remains the only unsolved case of air piracy in American commercial aviation history.
The physics of Cooper's jump are instructive. The Boeing 727-100 was flying at approximately 10,000 feet above ground level at an indicated airspeed of roughly 196 knots (approximately 225 miles per hour). The outside air temperature was approximately minus seven degrees Celsius. It was raining. Cooper jumped wearing loafers, a business suit, a trench coat, and a clip-on tie (which he left behind on the plane). He selected a military-surplus back parachute and a reserve chest pack. Notably, of the four parachutes provided, two were functional and two were dummies—intended for training. Cooper chose one functional back chute and one dummy reserve, suggesting either expert knowledge or consequential bad luck.
The aerodynamic challenges of a jump under these conditions are severe. At 196 knots, the blast of air exiting the rear stairway would have subjected Cooper to dynamic pressure exceeding 100 pounds per square foot—sufficient to strip clothing, dislocate limbs, and render controlled body positioning nearly impossible. The 727's airstair, when lowered in flight, creates significant turbulence immediately behind the aircraft. A jumper exiting into this turbulent wake without the protective equipment and training of a military paratrooper would face a high probability of being tumbled uncontrollably during the initial seconds of freefall.
Assuming Cooper survived the exit, he faced additional challenges. He jumped at night, over dense old-growth forest, in rain, without a helmet, altimeter, or reserve parachute (the one he selected was a non-functional training dummy). Landing in old-growth timber at night, even under a functional canopy, carries a high risk of fatal impact with tree trunks or entanglement in the canopy itself. The terrain below was the Cascades foothills—rugged, heavily forested, and in November, bitterly cold.
In 1980, an eight-year-old boy found $5,800 in deteriorating twenty-dollar bills on the bank of the Columbia River near Vancouver, Washington. The serial numbers matched the ransom money. No other bills from the ransom have ever surfaced in circulation—a remarkable fact given that $200,000 in sequential twenties would, if spent, inevitably appear in commercial banking channels.
The most economical explanation is that Cooper did not survive the jump. The physical demands exceeded what an untrained civilian could reasonably withstand, and the absence of the ransom money from circulation suggests it was never spent. But economy is not certainty. The case endures precisely because the evidence is consistent with failure but does not prove it. Cooper stepped off the back of a moving airplane, and the night swallowed him entirely.